


Flint and Tinder

by songlin



Category: Sherlock (TV)
Genre: Alpha Mycroft, Alpha/Beta/Omega Dynamics, Alpha/Omega, Dubious Consent, Incest, M/M, Mating Cycles/In Heat, Omega Sherlock, Omega Verse, Rimming, Scent Kink, Scenting, Sibling Incest, Unilock
Language: English
Status: Completed
Published: 2014-11-28
Updated: 2014-11-28
Packaged: 2018-02-27 07:15:54
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,527
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2684045
Author URL: https://archiveofourown.org/users/songlin/pseuds/songlin
Summary: <blockquote class="userstuff">
              <p>Sherlock does not want a keeper or a mate. He does not, under any circumstances, want an alpha. He is absolutely positive of this fact. Still, a brother—or this brother, at least—is not without advantages.</p>
            </blockquote>





	Flint and Tinder

**Author's Note:**

> Happy Thanksgiving; take me out with the rest of the garbage.
> 
> I was deliberately vague about Mycroft and Sherlock's ages during their previous encounter. It could have been a month prior to the story or years. Set it whenever you like. In this story, they are aged nineteen and twenty-six.
> 
> Also, no, I have no idea how this got finished before the WIPs I've been working on more often. Possibly because it was written entirely on my phone before going to bed? No, that's stupid, leave me in the trash.

"Mr. Holmes, I do apologize, but—"

Mycroft is well-practiced at the art of not-quite-fleeing insistent medical personnel who want to warn him off taking his brother home. He does not slow down. "With all due respect, Doctor, we prefer to utilize private hospitals."

The doctor is nodding impatiently. "Yes, but—"

"It isn't anything—"

"—the narcotics in his system and his general health exacerbated—"

"—believe me, I wish dearly this were the first time—"

"—transporting him in his current state is risky at—"

Mycroft and the doctor both stop in front of the door with the sign labeled "S. Holmes." Mycroft raises an eloquent eyebrow.

"I believe my case is made."

The room is empty. The sheets are wadded up at the foot of the bed and the pillows have been flung to all corners. An IV line is hanging awkwardly in space, the needle still swinging marginally back and forth.

"I," the doctor stammers, "I-I-I'm—we will devote all resources—"

Mycroft sighs. "No need, dear doctor. As I did mention, my brother's exploits are nothing new."

There are no belongings to pick up. Mycroft simply picks up the discharge papers and takes the lift upstairs.

The door to the roof is already unlocked and propped open with a stack of tongue depressors. Mycroft slips through and replaces the makeshift doorstop. He blinks for a moment, adjusting to the dim glow of London at nighttime from a rooftop. When his vision clears, he spots the slim figure sitting on the edge of the roof with his legs hanging over the edge. As Mycroft watches, he tips his head back and breathes out a long plume of smoke.

"I should remind you hospitals are generally non-smoking areas," Mycroft says.

Sherlock swings his legs over and turns round. Mycroft's face nearly betrays his shock. Now that he can see it close-up and in person, Sherlock's face is worryingly thin, bordering on gaunt. His stolen scrubs hang loose over his ribcage. Mycroft schools himself into careful stolidity.

"We're not in a hospital," Sherlock says, taking a defiant drag from his cigarette.

"Trivialities," says Mycroft. "Do come in."

Sherlock sneers. "What, so you can have me committed? No thank you."

"You'll be pleased to hear you've been discharged."

For a fraction of a second, Sherlock forgets to watch his expression, and a brief flash of surprise flickers over his face. But then he recovers, and he is cool and indifferent again.

"What do you want?"

"Is it not enough to want to spare my brother a pointless stay in hospital?"

Sherlock scoffs, then winces.

Mycroft frowns. Now that he has the opportunity for closer inspection, Mycroft can clearly see his brother is not himself. Sherlock is not just thin-faced, he's pale and sweaty. The hand holding the cigarette is shaking, and he's got the other tucked under his arm. Even from this distance, Mycroft can discern the fine tremors through Sherlock's body.

And then the wind catches, a light breeze blows from Sherlock's direction, and Mycroft's senses light up. A chill runs down his spine. They have less time then he thought, if a mere whiff from that distance is enough to—make him want to—make him picture—make him _need_ —

Mycroft blinks, and is under control.

"Sherlock," he says, "surely you agree that spending—however long with me as I take you to a safe place is preferable to spending the next two to four weeks locked up in Bart's." Sherlock does not look convinced. Luckily, Mycroft is a forward planner.

"After you're feeling yourself again, I will make sure that Mother hears of none of this."

Mycroft knows his brother catches the veiled threat by the look in his eyes. Of course, he ignores it. He has always been too stubborn for anyone's good.

"'Feeling myself'?" He sneers. "Call it what it is. I'm in _heat."_ He spits the word, boiling with disgust, and flings the butt of his fag over the edge of the building and out into the wind.

Mycroft merely says, "Very well." He extend a hand. "Shall we?"

Sherlock glares distrustfully at Mycroft's hand, then at his face, and then out into the city.

The moment he caves is visible. Mycroft sees it, captures it, and locks it away in that shameful place with all the others.

———

Sherlock does not want a keeper or a mate. He does not, under any circumstances, want an _alpha_. He is absolutely positive of this fact.

Still, a brother—or _this_ brother, at least—is not without advantages. Eventually, Mycroft will get Sherlock what he does want. At present, what he needs is to _leave_. Hospitals are horrid, and he feels horrid, and he would much rather feel horrid somewhere marginally less appalling.

There was that student flat. It was hardly appalling at all. It had Victor, and a skull, and space for Sherlock's experiments, and a landlord who wasn't entirely dull.

Or it did, at least. Sherlock swallows hard and stows the student flat (and Victor— _not_ Victor— _and Victor)_ in the back for later deletion.

He follows Mycroft into the hospital, down to the garage, and into his car.

———

Sherlock curls up against the window, despite the ample room in the backseat. Mycroft raises his voice so the driver can hear him through the screen she's put up.

"Marcella, home, please."

As the car pulls away from the curb, Sherlock sneers through his discomfort. "What? Do you have a room to leave me in there? To _ride it out?"_

"Sherlock—"

"I don't need it. Just leave me—" He halts and grimaces, clenching his teeth against a...pain? Does it hurt yet, in these earlier stages? Whether or not it does, Mycroft winces in sympathy.

There's another feeling there, a far less admirable one, but Mycroft drives it out even as it sniffs at the tendrils of forbidden scent in the air.

"Alone," Sherlock finishes with a scowl.

Mycroft is struck with a sudden vision of exactly what Sherlock will be doing in that room, alone, and brutally wrestles it down.

"That is the general plan," he says.

Sherlock scowls. "There is no 'alone' in your ridiculous monstrosity of a home."

That is unfair, but not untrue, so Mycroft does not argue the point.

The drive continues. 

———

Sherlock grinds his teeth. He is shaking, that whole-body, uncontrollable fever-shiver. Does this always happen? He's not in heat often enough to know, and he deletes as much of it as he can.

Mycroft's voice filters in through the haze. "...might consider it before you disappear for a binge again," he is saying.

Sherlock sneers. "Oh, yes," he spits. "Heaven forbid I embarrass you in front of your new friends." It comes out much more childish than it seemed in his head.

Mycroft sighs and looks out his window. "I'm not embarrassed, Sherlock," he says. "I'm...disappointed."

Sherlock rolls his eyes and wipes sweat off his brow with his shirtsleeve. "Spare me your pseudo-parental theatrics and get me home," he says.

In retrospect, he realizes it sounded much more like a plea than a demand. Moments later, he loses coherence as a wave of hormones and heat rushes through him and his insides cramp up in search of a knot. He bites into the base of his thumb. It brings back a little sense, but not enough.

The hand on his shoulder is jarring, and not unpleasantly so. "Sherlock?" Mycroft says, his tone tempered with concern. "What's wrong?"

Sherlock can't respond for a moment. He is too busy rocking back into the seat, trying to get enough pressure to ease the discomfort. The movement makes his legs slide against each other in a way that isn't as uncomfortable as it should be.

"Sherlock?"

"What's wrong is I'm in heat," he snaps at last. "Tell your idiot driver to step on it."

Mycroft leans forward. "How far out are we, exactly?"

"Three hours, at a guess," she says.

Sherlock groans. He _cannot_ wait three hours before he gets something in him. He cannot. He will die. _Can_ he die? Can sexual desperation kill you? God, he hopes not.

He takes a deep, shaky breath and really, _really_ hopes he didn't say any of that out loud.

"Actually, Marcella, we may stay somewhere for the night. I'll put you up, of course."

Marcella nods. "Yes, sir. Where should I be looking to stop?"

"The first suitable place will do. Proximity outweighs luxury at the moment, I think."

Sherlock pulls his feet up onto the seat. God, this is _awful_. He's _so_ hard, and _so_ wet, and every inch of skin is so sensitive as to be chafed raw by the contact of skin and fabric, and his stomach _aches_ from the hours of useless muscle cramps in search of a knot, and his face is flushed and warm, and his fingers are trembling, and his teeth are chattering, and all he needs is for someone to so much as touch him and he'll just _disintegrate_.

The car rolls to a stop. Mycroft is saying something. Sherlock pays it no mind until he starts to get out of the car.

"No!" he says, and immediately bites it back.

Mycroft gives him a curious look. "I'm only arranging a room. Shan't be a moment."

Sherlock looks away. "Yes. Naturally."

Mycroft gets out and shuts his door. Sherlock starts to sink down into black disappointment, but then he comes around to the other side, opens Sherlock's door, and offers him his hand. Sherlock is proud, but he's not that proud. He accepts the help and then does not push away when Mycroft rests his hand in the middle of his back. Sherlock is struck with a sudden, clear memory of being six years old and learning to ride a bicycle, and not willing to go without Mycroft's hand on his back. He hadn't needed it, now that he thinks. He had the basics down: balance, steering, brakes. All the same, he had been terrified that the moment Mycroft wasn't supporting him, he'd careen off into disaster.

Of course, Mycroft had never left him live it down.

It takes _forever_ to settle the rooms. Apparently, there is a convention staying there, and they are fully booked. Sherlock doesn't listen to most of it. He is busy finding the optimum position in which to curl up and hide his face.

After about an age, Mycroft's hand settled on his shoulder. "Sherlock."

_"What,"_ Sherlock snaps.

"I've gotten you a room here. Marcella and I shall find another—"

_"Nooo,"_ Sherlock groans, then slaps a hand to his mouth.

Mycroft frowns. "Sherlock, I don't think it wise that I—"

"Ugh. Dull."

Mycroft shuts his eyes, breathes in deeply, then sighs. "I suppose I should send Marcella on her way."

Sherlock tucks his face back into the crook of his arm while Mycroft leaves to get their bags and apprise his driver of the situation. He shivers and breathes through a spasm. It lasts…a while. Doesn't matter. Some time.

There is a different hand on his arm. Not Mycroft's. Smaller. Lighter. _Wrong_.

"Hey, there, pretty thing," the concierge croons. "Hurts, doesn't it?" She is stroking her thumb back and forth over his arm, and it grates on Sherlock's every nerve. "I could help you, sweetheart. If you wanted. God, you smell so good."

Sherlock is lifting his head to snarl when the concierge's hand is wrenched away and she cries out. Mycroft is standing behind her, having twisted her arm up behind her back. She whimpers in pain. Mycroft jerks her arm up a little higher and she contorts backwards with a yowl.

"I suggest," he says, in tones like a January ice storm, "that you give me our keys and let us go on our way."

Heat floods Sherlock's face. He gasps and hopes it goes unnoticed. The concierge is babbling, a long string of "yes sir my apologies sir it's no problem sir." Mycroft releases her with a sneer and she scampers to fetch their keys. Mycroft watches her go until he is satisfied, then stoops to Sherlock's level.

"My apologies. I should have known better than to leave you unattended."

Sherlock grits his teeth and shakes his head. He cannot speak just now, not without betraying himself. He _must not_ speak.

They get up to their room without much trouble. Sherlock collapses on the bed before the door even clicks shut.

"I'm going to shower," Mycroft says. "The door is locked."

Sherlock doesn't even make a sound of acknowledgment. The door must shut at some point, but Sherlock doesn't hear. He is too busy trying to stop thinking about the vicious look on his brother's face when he twisted the concierge's arm, and the feeling of rapturous triumph in his belly, and the way his face flushed and his cock plumped up.

Sherlock's stomach cramps again. He whines and loses himself in his body.

———

Mycroft, meanwhile, is trying to shake it off.

The doctor was right. This is no normal heat. Mycroft shouldn't be anywhere near this sensitive to his brother's unique pheromone cocktail, but damned if he isn't. He wrenches the cold water knob to the left and tries to ignore his throbbing erection.

_The fact is,_ he thinks, _that it was always going to come back to haunt you._

Mycroft soaps himself up and doesn't picture Sherlock's soft curls and bright eyes, or Sherlock's murmured promises to keep everything a secret.

He scrubs his fingers through his hair and doesn't remember his teeth digging into his lip or Sherlock's hand dipping inside Mycroft's dressing gown.

He rinses himself off and doesn't think about the streaks on Sherlock's hand after he withdrew it, and the way they glistened in the darkness, and the way they made Mycroft swell with possession and fierce, vicious desire, and the way he kissed him, kissed him like he was gorging himself on Sherlock, on that very moment—

—the moment that Mycroft has _definitely, completely forced out of his memory._

Mycroft towels himself off with much more aggression than necessary. _He_ is in control of his body, not any cross-wired mating instincts. He stops and takes a deep breath. Control.

Too late, he realizes that his pajamas are in the next room, so he wraps the towel around his waist, takes a deep breath, and opens the door.

The scent knocks him back, staggering. He'd no idea how fast this was going to progress, but it was clear that the answer is even worse than predicted.

Sherlock's bed is empty. The bedding has been tossed onto the floor and Sherlock's shirt has been flung clear across the room. When Mycroft emerges fully, he finds his brother on the floor between the two beds, his head to his knees as he rocks back and forth. He is still wearing the thin hospital scrub bottoms, but nothing else. Mycroft averts his eyes from the dark, damp patch just visible.

"Mycroft," Sherlock says, without lifting his head. "God, _ah_ , you have to do something. Please. _Please_."

_He can't mean..._

"I tried to do it myself," he pants, and Mycroft sucks in a breath, "but it was—wasn't enough."

Mycroft grits his teeth. "Sherlock. You are...not well. Don't ask for what you would not if—"

Sherlock snarls and slaps a hand to the floor. _"What I wouldn't want'!_  You're all of you so determined to tell me what I want, as if this— _biological weapon_ renders me incapable of knowing my own mind. If these...urges are my disease, why can't I choose the treatment? If I am to be reduced to begging, I would like at least to be allowed to do it." He laughs and scratches his fingers through his hair. "I'm _aroused_ , Mycroft, I'm not _deranged_."

This fit of coherence is cut off with a shudder and a cry that Sherlock isn't even trying to hold back anymore. He doubles over, clutches his stomach with both hands, and chants a quiet prayer of curses under his breath. Shamefully, Mycroft's cock throbs.

Sherlock lifts his head. "Come on," he says raggedly. "It's not as if we haven't—"

_ "Don't—"  _

"Oh, don't pretend!" Sherlock flies to his feet and stalks towards hims. Mycroft turns his head aside, but doesn't move away. "And don't crawl into some fit of self-loathing. It was harmless. Consensual experimentation."

Mycroft shakes his head, tight-lipped. "We were in little position to determine what constituted consent."

"Luckily, at present, we are," says Sherlock. "I convinced you once, I'm convincing you again."

"And yet, here I am: unconvinced."

Sherlock's eyes drag down Mycroft's body slowly to the bulge in his trousers, then flick back up with a smirk. "In that case, do inform the rest of your body, if you can find it underneath the extraneous skin."

"Ah. Insulting my physique, now, are we? I take it we've utterly abandoned seduction." Mycroft regrets the words immediately. They're close to flirting, dangerously close, and if he's not careful—

Sherlock sways closer. His voice drops down to a subsonic purr. " _Have_ we abandoned seduction?"

_Damn_.

Mycroft licks his lip. Sherlock's eyes track the movements of his tongue.

"We ought to."

"We ought to have finished the drive home tonight," Sherlock counters.

Just picturing that—trapped in the car with Sherlock writhing in the backseat, smelling like bedhead and rumpled sheets and love bites—is enough to drive Mycroft half out of his mind. He loses himself to the picture for no more than a moment, and loses control. When he snaps back, he has pinned Sherlock to the bed by the wrists.

Sherlock's pleased little laugh shatters into a swallowed groan. He shifts underneath of Mycroft, trying to breathe until he can function again. "Good," he sighs, when he's got his wits back under him. "Like that."

Mycroft tries to scramble away, but Sherlock is too quick. He grabs Mycroft's hands where they're holding his wrists, trapping Mycroft who's trapping Sherlock who's trapping...Mycroft blinks slowly. He isn't thinking sensibly.

Then Sherlock just...melts. His edges seem to soften, eyes lips hands body going lax and limp and tired like a worn, helpless thing. Mycroft swallows around the tight feeling in his throat. He knows what Sherlock is doing, what he's trying, and he will _not_ —he will _not_ be ensnared by it—

"Please," Sherlock whispers. He shudders delicately, looking every bit the virgin Mycroft knows damn well he isn't. "It hurts."

His voice cracks on the last word just as he curls upwards into another shudder, and that can't _all_ be for show. Even he couldn't playact it that well. Besides that, Mycroft is not entirely surprised to find that he _does not care._

When Mycroft bends to kiss Sherlock, he cannot shake the mental image of God breathing life into Adam. Was it this tentative, or this exciting? Did Adam gasp in his first breath as if he would burst without it, as Sherlock does? Mycroft knows he feels markedly godlike as he runs his hands down Sherlock's body and feels Sherlock shape his body to his brother's hands.

"Again," Sherlock says.

Now that he's had the taste, he can't resist. He drags him up by the shoulders and surges forward to kiss him again. Sherlock presses their bodies flush together as he combs his fingers back through Mycroft's short hair over and over and over, which gives Mycroft the idea to do the same. God, Sherlock's hair. When they were children, Mycroft would sometimes muss it up just to steal the opportunity to touch it. Given the chance to crush those curls between his fingers to his heart's content, he goes wild.

Sherlock is whimpering into his mouth and shaking and then all of a sudden pressing his erection up into Mycroft's. Mycroft exhales with a little "ha," barely vocalized. He drives his hips down into Sherlock's, pins him to the bed, and rocks back and forth. The slow grind of their cocks is exquisite. It's intoxicating. It's...not enough.

"Come _on_ ," Sherlock moans. He tugs at Mycroft's shirt. "Get _naked_ , make this _stop_ already, won't you?"

Mycroft kneels up, untucks the towel from around his waist, unwraps it, and casts it aside. Sherlock, between his legs, flushes pink and grits his teeth as his body strains, clutching at Mycroft's leg.

"I'm," Sherlock says, and "It's," but he can't string the words together before a violent tremor racks him. He cries out and writhes, hips squirming under the heady influence of need.

"Please!" Sherlock squeezes his eyes shut and— _God_ , no—tears well up in the hollow of his eyes and streak down his face, involuntary and uncontrollable. "It hurts."

"I— _God_."

Mycroft flings the towel...somewhere. He climbs off Sherlock, meaning to strip him bare. But Sherlock beats him to it, shucking the flimsy hospital scrubs down and off. Mycroft is nearly bowled over. The pheromones that had been driving him mad all day are everywhere, thick and rich and heady.

He is moving before he knows it. He presses Sherlock's knees apart, bows between them, and licks a stripe down Sherlock's inner thigh from knee on up that ends with his nose nearly buried in him. Sherlock's legs jerk. He keens, arches his back, hooks his hands behind his knees, and pulls them up towards his chest to bare his glistening hole to his brother. Mycroft's animal instincts are perfectly capable of processing this request. He begins by planting his mouth just to the left of Sherlock's arsehole, over a streak of fluid. Sherlock whines, but Mycroft is insistent. He laps at the spot with slow drags of his tongue. It's less of a tease, more of a promise, though he doubts Sherlock sees it the same way. The taste of eager omega is setting off chemical reactions in his bloodstream like fireworks. He sighs, and the rush of air makes Sherlock shiver.

When Mycroft lifts his head to catch his breath, he realizes the side of his face is cold. He touches it and his fingers come away damp.

_Sherlock is...dripping. All over my face._

There is a moment where Mycroft is still processing this information. It takes longer than it would, because most of his brain has ceased to function under normal operations. Then he moves.

He spreads Sherlock's arsecheeks—Sherlock gasps from the sudden shock of pleasure—presses his mouth the the gap between them, and licks a wide path over Sherlock's hole.

It's different, with an omega in heat. More like cunnilingus. There's very little resistance to work his tongue past, and it's wet of its own accord. But no one Mycroft has been with has soaked his face like this, all the way down to his neck and hair, or sobbed quite like this when he reached a deeper spot, or tasted like this—like a _gift_.

Mycroft becomes aware of two things. First, Sherlock is talking. It's nothing coherent, just a series of barely incomprehensible pleas. Second, his cock is _aching_. He reaches down to give it a squeeze and nearly chokes. He's painfully sensitive, and when he tentatively feels downwards, his fingers brush over his knot. Just that mild contact sparks a stab of need through him, a desperation to _have_. He is moving before he realizes it, clambering to his knees and forcing Sherlock over onto all fours, pushing Sherlock's head down, smearing the head of his cock down Sherlock's crack, notching in, and pushing in with a sharp thrust.

Sherlock's body jerks. He gasps and struggles to raise the front of his body up on his arms, but Mycroft keeps his neck pinned fast. He isn't thinking now. There is nothing left of his brain but _take, take, take._

So he takes everything.

———

Sherlock is on _fire_.

He remembers his first heat, fifteen and sobbing and scrabbling at the windows, trying to get some air because he had realized just why they call it "heat." The windows were locked, of course, and there had been no one to drive the itch away, only his clumsy hands failing to plug him up the way he craved.

There is none of that now.

He writhes and cries under his brother. He is pinned down at the neck, scruffed like a mewling kitten and just as helpless. He can feel the knot outside of him, and it must be fully swollen, surely, because that is barely going to fit. He is terrified, and he is _thrilled_. What if Mycroft forces it in? It could tear Sherlock apart. God, _please_ let him shove it in.

Mycroft stops with that bulge just teasing the rim. Sherlock whimpers. Mycroft grunts in response and pushes his head down harder.

"Take it," he growls, and rams it in.

Sherlock screams. It's so much, too much, and yet he needs more. He is stretched tight around the knot. It's...large. Quite possibly the size of Sherlock's fist. And he wants it to _destroy_ him.

Mycroft obliges. He moves, and Sherlock realizes it wasn't fully formed after all, because he can still slide it out and shove it back in. Sherlock shouts, equal parts exultation and shock, and then Mycroft does it again. And again. And...

Sherlock retreats deep into his body. He ceases to be and narrows down to just this, this animal creature lost in mindless rutting. They could be in the middle of Hyde Park for all he cares, or in the parlor at home, or in some primordial jungle. He _does not care_. He is a creature of base instincts and nothing more.

He is just beginning to grow frustrated with the lack of progress when Mycroft's hold on the back of his neck tightens and he shoves Sherlock's head down into the pillows. Sherlock snarls and struggles, but Mycroft holds him fast.

_"Mine,"_ he growls.

God, he sounds _nothing_ like himself. He sounds...serrated, as if his voice could saw Sherlock through.

Sherlock twists and keens. Mycroft just fucks him all the harder. Sherlock is panting out soft, wordless little cries. Something is building, tightening, straining—

He comes for ages. The back of his thigh cramps and it doesn't even register. Everything is the quick contractions of muscle around Mycroft's cock injecting Sherlock with ecstasy. Mycroft comes too near the end of it, for much less time. It makes Sherlock purr with satisfaction and arch back into him.

After, they curl up together and rock lazily back and forth in the quiet haze of knotting. Sherlock doesn't care for it, but he does enjoy orgasms, so knotting is a necessary evil when in heat.

"They don't matter, you know," Mycroft says.

"What?"

"Anyone else. We burn them out, we two."

Sherlock does not think of Victor back at school, the snapped nerves and screamed insults and slammed doors that preceded all of…this.

"It's better this way," Mycroft murmurs into the back of Sherlock's neck. "We suit each other."

Mutely, Sherlock checks the clock on the bedside table and finds he's at least twelve hours to go before his heat ends.

So he nods like he understands and leans back into his brother's touch. "Yes."

 


End file.
